by Staff Writers
Riverside CA (SPX) Mar 11, 2016
A team of researchers, led by a group at the University of California, Riverside, have demonstrated for the first time the transmission of electrical signals through insulators in a sandwich-like structure, a development that could help create more energy efficient electronic devices.
Conventional electronic devices rely on the transport of electrons in a semiconductor such as silicon. Now, researchers are exploiting the 'spin' of the electron rather than its charge to create a new generation of 'spintronic' devices that are potentially more energy efficient and more versatile than those currently making up silicon chips and circuit elements.
The UC Riverside-led research, which was published online Wednesday (March 2) in the journal Nature Communications, is significant because it demonstrates that a tri-layer, sandwich-like, structure can serves as a scalable pure spin current device, an essential ingredient in spintronics.
A key element in this breakthrough is the material. To demonstrate the effect, the magnetic insulator needs to be truly insulating, or there will be a parasitic signal from leakage. On the other hand, a high-quality magnetic insulator grown on metal had never been demonstrated.
Using combination of sputtering (for metals) and pulsed laser deposition (for insulator), we successfully showed that the 50-100 nanometer thick magnetic insulator, such as yttrium iron garnet, is not only magnetic and insulating, but also of high quality when it is grown on 5 nanometer thick platinum.
In the structures used by the researchers, there are two metals and a magnetic insulator in between. The metals are for spin current generation and detection (conversion of spin current back to charge current) via the so-called spin Hall effect and inverse spin Hall effect.
The magnetic insulator is an electrical insulator but a good spin current conductor. The spin current flowing in the insulator does not involve mobile electrons therefore it does not dissipate energy as an electrical current does in joule heating.
The researchers have also demonstrated that the signal transmission can be switched on and off and modulated in its strength by a magnetic field. The electrical signal transmission through the magnetic insulators can be switched on and off depending on the magnetic state, or direction of the magnetization, of the magnetic insulators.
So the direction of the magnetization can be regarded as a memory state of non-volatile random access memory devices. In addition, the signal level can be modulated by changing the direction of the magnetization; therefore, it can also be used as analog devices. The sandwich structure can be made small by nanofabrication so that the devices can be scaled down.
Science paper: "Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta)trilayers." The authors are Jing Shi, a UC Riverside physics professor; five members of his lab, Junxue Li, Yadong Xu, Mohammed Aldosary, Chi Tang and Zhisheng Lin; Roger Lake, a UC Riverside professor of electrical and computer engineering; and Shufeng Zhang, a physics professor at the University of Arizona.
University of California - Riverside
Computer Chip Architecture, Technology and Manufacture
Nano Technology News From SpaceMart.com
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|